Mars magmas once contained a lot of water MIT News

Evidence from a Martian volcanic rock indicates that Mars magmas contained significant amounts of water before eruption on the planet’s surface, researchers from the Massachusetts Institute of Technology, the University of Tennessee and other institutions report in the Jan. 25 issue of Nature. Scientists say that channels on Mars’s surface may have been carved by flowing water and an ancient ocean may have existed there, but little is known about the source of the water. One possible source is volcanic degassing, in which water vapor is produced by magma spewing from volcanos, but the Martian rocks that have reached Earth as meteorites have notoriously low water content. This study shows that before the molten rock that crystallized to form Martian meteorites was erupted on the surface of the planet, it contained as much as 2 percent dissolved water.